RFID label technique

ABSTRACT

An RFID webstock containing a relatively high pitch-density array of semiconductive chips is provided and joined to a web bearing relatively widely spaced antennas in a continuous process. The RFID webstock is separated or cut into individual chip sections, with the spacing of the chips being increased as the RFID webstock is die cut. The individual chips on the sections are then joined to corresponding antennas to form an RFID inlay stock. This process is conducive to high speed roll-to-roll production of RFID tag and label roll stock.

CROSS-REFERENCE

This is a continuation of U.S. application Ser. No. 10/323,490, filedDec. 18, 2002, which claims priority to U.S. Provisional PatentApplication No. 60/350,606, filed Jan. 18, 2002. This application isalso related to U.S. patent application Ser. No. 09/776,281, filed Feb.2, 2001, subsequently published as U.S. Patent Publication No.2002/0149107 A2. All of the above applications are herin incorporated byreference in their entireties.

BACKGROUND OF THE INVENTION

1. Field of the Invention

This invention relates to the field of Radio Frequency Identification(RFID) tags and labels, and to particular methods of manufacturing them,including a roll-to-roll method of manufacture and an alternativesheet-to-roll method of manufacture.

2. Prior Art

RFID tags and labels have a combination of antennas and analog and/ordigital electronics, which may include for example communicationselectronics, data memory, and control logic. RFID tags and labels arewidely used to associate an object with an identification code. Forexample, RFID tags are used in conjunction with security-locks in cars,for access control to buildings, and for tracking inventory and parcels.Some examples of RFID tags and labels appear in U.S. Pat. Nos.6,107,920, 6,206,292, and 6,262,292, all of which this applicationincorporates by reference.

RFID tags and labels include active tags, which include a power source,and passive tags and labels, which do not. In the case of passive tags,in order to retrieve the information from the chip, a “base station” or“reader” sends an excitation signal to the RFID tag or label. Theexcitation signal energizes the tag or label, and the RFID circuitrytransmits the stored information back to the reader. The “reader”receives and decodes the information from the RFID tag. In general, RFIDtags can retain and transmit enough information to uniquely identifyindividuals, packages, inventory and the like. RFID tags and labels alsocan be characterized as to those to which information is written onlyonce (although the information may be read repeatedly), and those towhich information may be written during use. For example, RFID tags maystore environmental data (that may be detected by an associated sensor),logistical histories, state data, etc.

Methods for manufacturing RFID labels are disclosed in PCT PublicationNo. WO 01/61646 by Moore North America, Inc., incorporated herein bythis reference. The method disclosed in PCT Publication No. WO 01/61646uses a number of different sources of RFID inlets, each inlet includingan antenna and a chip. A plurality of webs are matched together and RFIDlabels are die cut from the webs, to produce RFID labels with liner.Alternatively, linerless, RFID labels are produced from a composite webwith a release material on one face and pressure sensitive adhesive onthe other, the labels formed by perforations in the web. Variousalternatives are possible.

Still other RFID devices and methods for manufacturing RFID labels aredisclosed in United States Patent Application Publication No. U.S.2001/0053675 by Plettner, incorporated herein by this reference. Thedevices include a transponder comprising a chip having contact pads andat least two coupling elements, which are conductively connected withthe contact pads. The coupling elements are touch-free relative to eachother and formed in a self-supported as well as a free-standing way andare essentially extended parallel to the chip plane. The total mountingheight of the transponder corresponds essentially to the mounting heightof the chip. The size and geometry of the coupling elements are adaptedfor acting as a dipole antenna or in conjunction with an evaluation unitas a plate capacitor. Typically, the transponders are produced at thewafer level. The coupling elements can be contacted with the contactpads of the chip directly at the wafer level, i.e., before the chips areextracted from the grouping given by the wafer.

In many applications, it is desirable to reduce the size of theelectronics as small as possible. Applicants' assignee Avery DennisonCorporation has been working with Alien Technology Corporation andothers to identify materials, devise constructions, and developprocessing techniques to efficiently produce rolls of a flexiblesubstrate filled with “small electronic blocks”.

Considering the flexible substrate filled with “small electronicblocks,” Alien Technology Corporation (“Alien”), of Morgan Hill, Calif.,for example, has developed techniques for manufacturing microelectronicelements as small electronic blocks, which Alien calls “NanoBlocks”, andthen depositing the small electronic blocks into recesses on anunderlying substrate. To receive the small electronic blocks, a planarsubstrate 200 (FIG. 1) is embossed with numerous receptor wells 210. Thereceptor wells 210 are typically formed in a pattern on the substrate.For instance, in FIG. 1 the receptor wells 210 form a simple matrixpattern that may extend over only a predefined portion of the substrate,or may extend across substantially the entire width and length of thesubstrate, as desired.

To place the small electronic blocks into the recesses, Alien uses atechnique known as Fluidic Self Assembly (“FSA”). The FSA methodincludes dispersing the small electronic blocks in a slurry, and thenflowing the slurry over the top surface of the substrate. The smallelectronic blocks and recesses have complementary shapes, and gravitypulls the small electronic blocks down into the recesses. The end-resultis a substrate (e.g., a sheet, a web, or a plate) that is embedded withtiny electronic elements. FIG. 2 illustrates a small electronic block100 disposed within a recess 210. Between the block 100 and thesubstrate 220 is a metallization layer 222. The block 100 has a topsurface with a circuit 224 disposed thereon.

Alien has a number of patents on its technique, including U.S. Pat. Nos.5,783,856; 5,824,186; 5,904,545; 5,545,291; 6,274,508; and 6,281,036,all of which the present application incorporates by reference. Furtherinformation can be found in Alien's Patent Cooperation Treatypublications, including WO 00/49421; WO 00/49658; WO 00/55915; WO00/55916; WO 00/46854 and WO 01/33621, all of which this applicationincorporates by reference. Another recent publication of interestappeared in the Information Display, November 2000, Vol. 16, No. 11 atpp. 12-17, and in a paper published by the MIT Auto-ID Center, entitled,“Toward the 5 Cent Tag,” published in February 2002. Further detailsregarding the manufacture of the microstructure elements and the FSAprocesses may be found in U.S. Pat. Nos. 5,545,291 and 5,904,545, and inPCT/US99/30391 at WO 00/46854, the entire disclosures of which arehereby incorporated by reference.

As set forth in the MIT Auto-ID Center publication cited above, theelectronic blocks may be located in the openings by a vibratory feederassembly, such as that developed by Philips, instead of the FluidicSelf-Assembly method. Alternatively, the electronic blocks may belocated into the openings with a deterministic pick and place method,which can use a robot arm to pick the electronic elements and place themone at a time into respective openings, as described in U.S. Pat. No.6,274,508.

In yet another approach to locating the electronic blocks, the webstockor sheetstock may include openings that extend through the entirethickness of the sheet. A vacuum may be applied below the webstock topull the electronic blocks into and to fill the openings.

The present invention addresses a significant need in these methodsinvolving the placement of small electronic blocks or chips in oropenings of a flexible substrate, as well as in more conventionalsurface mounting techniques for placing chips on flexible substrates.That is, it can be desirable to space the chips at densities exceedingthe densities of antennas to which the chips later are bonded, e.g.antennas formed on webstock. The present invention provides thiscapability, furthermore, using techniques well suited to high speedroll-to-roll production of RFID tags and labels.

SUMMARY OF THE INVENTION

This invention relates to methods of making articles for RFID (RadioFrequency Identification), such as tags or labels. These methods processflexible webstock or sheetstock with embedded or surface mountedchips—herein called “RFID webstock” or “RFID sheetstock”, respectively.

As used in this patent application, the “pitch” of elements on awebstock or sheetstock (such as chips within an RFID webstock, or labelswithin a label stock) means the center-to-center distance betweenadjacent elements. In the present invention, the pitch of chips may bedifferent than the pitch of an array of RFID tags or labels to beformed: (a) in the longitudinal (also called the “down web”) direction;(b) in the transverse (or “cross web”) direction, or (c) in bothdirections. As used in the present patent application, the “pitchdensity”, or the number per unit area e.g. of chips, is determined bycalculating the reciprocal of the product of these pitches.

In accordance with one aspect of the roll-to-roll manufacturing method,the pitch density of the chips in RFID webstock or RFID sheetstock isdifferent from (preferably significantly greater than) the pitch densityof the individual RFID tags or labels within the roll of tags or labels.The difference in pitch density results from a difference in pitch inthe down-web direction, in the cross-web direction, or in bothdirections. Typically the pitch of the chips along each axis of the RFIDwebstock is less than or equal to the pitch of antennas along thecorresponding axis of the antenna web. This difference in chip densityis attributable to the separation of the RFID webstock into “sections”,and the adjustment of pitch density (“indexing”) of these sections inthe roll-to-roll lamination process. In one embodiment, the RFIDwebstock is die cut into a series of sections each containing a crossweb column of chips, and the down-web pitch of chips is increased priorto lamination of the sections to a web containing antennas to form anRFID inlay stock. In another embodiment, the RFID webstock is die cutinto a series of sections each comprising a lane containing a down-webrow of chips, and these lanes are then spread or separated to increasethe cross-web pitch of chips prior to lamination of the sections to aweb containing antennas. In a third embodiment, an RFID webstock isfirst slit into lanes, and then individual sections are cut or separatedfrom each lane in order to adjust the down-web pitch of the individualchip sections.

The method of the invention is adapted both to the use of RFID webstockand RFID sheetstock-as a carrier for RFID chips, the former being highlypreferred. The term “RFID microelectronic stock” is used to encompassboth RFID webstock and RFID sheetstock. These terms identify thewebstock or sheetstock including RFID chips and electrical connectors,but before joining to antennas. Once the individual chips are associatedwith corresponding antennas, this patent application uses “RFID inlay”to identify individual chip-antenna assemblies, and the term “RFID inlaystock” to identify a webstock containing such RFID inlays.

In a preferred embodiment, the pitch density of the chips in the RFIDinlay stock is the same as the pitch density of the chips in the finaltag or label stock. However, it is possible further to adjust the pitchdensity of the individual RFID inlays and chips as they are integratedinto the final tag or label stock.

According to one embodiment of the invention, a method of forming anRFID article includes providing an RFID webstock having a plurality ofrecesses, each of the recesses containing an RFID chip. A second web isprovided having antennas spaced thereon. The RFID webstock is divided(e.g. severed, or separated) into a plurality of sections, each of thesections including one or more of the RFID chips. The pitch of the RFIDsections is indexed from a high pitch density on the RFID webstock, to arelatively low pitch density on an RFID inlay stock. The sections areattached to a plurality of antennas in an automatic continuous process,so that each of the RFID chips is joined to (placed in ohmiccommunication with) one of the antennas to form an RFID inlay stock.

According to another embodiment of the invention, a method of forming anRFID article includes providing an RFID webstock of polymeric materialhaving an array of RFID chips. A second web is provided having antennasspaced thereon. The RFID webstock is divided into a plurality ofsections, each of the sections including one or more of the RFID chips.The pitch of the RFID sections is indexed from a relatively high densityon the RFID webstock, to a relatively low density on an RFID inlaystock. The sections are attached to a plurality of antennas in anautomatic continuous process, so that each of the RFID chips is adjacentto one of the antennas to form an RFID inlay stock.

According to other embodiments, the dividing and indexing steps may beeffected using a cutter member and a transport member, the RFID webstockbeing passed through a cutting location between the cutter member andtransport member, wherein sections are cut from the RFID webstock andengaged by the transport member. The transport member may conveysections from the cutting location to a transfer location at which eachof the sections is joined to an antenna. The cutter member and transportmember may be, for example, rollers or belts. The transport member mayengage sections with vacuum holders or clamps.

In the indexing step the down-web spacing of RFID chips on the RFIDwebstock may be increased on the transport member, to match the spacingof antennas to which these chips are joined at the transfer location.The indexing step may further include the step of transporting the RFIDwebstock so as to effect indexing of the down-web pitch of the RFIDchips relative to the pitch of these chips on the transport member.

A step of indexing in the cross-web direction may be done by, forexample, slitting the RFID webstock of polymeric material into lanes,and spreading the lanes apart. The lanes once separated can travel alongdiverging paths, or can be realigned to be travel along parallel paths(of increased cross-web pitch in comparison to the original cross-webpitch).

Another embodiment of the indexing step is to divide the RFID webstockinto a series of cross-web columns of chips, which can be engaged on thetransport member and indexed separately from other columns of chips.

The attaching step may be effected by pressing the transport memberagainst a lamination member at the transfer location, at which thesection and antenna web pass through a nip or an extended zone ofcontact between the transport member and lamination member. For examplethe transport member and lamination member may both comprise tworollers, or a roller and a belt, or two belts.

In another specific embodiment, the method may further compriseunrolling a first facestock roll and laminating the first facestock rollto the RFID inlay stock. A second roll of facestock may be unwound, andthe facestock from the second roll may be attached to the RFID inlaystock opposite the first facestock. The method may further include thestep of forming an adhesive label.

The antennas may be formed in any of a number of different ways such as,for example, (i) printing conductive ink; (ii) sputtering metal; (iii)laminating foil; and (iv) hot-stamping.

Considering aspects of the invention further, in one embodiment of aconverting assembly to separate RFID sections and join them to antennas,the RFID webstock is severed into sections by passing the webstockthrough a cutting location between a cutter member and a transportmember. Preferably, the transport member acts as an anvil as sectionsare cut from the RFID webstock. In one embodiment, the transport memberand cutter member are rollers; alternatively one or both of thesemembers may comprise a belt. The transport member may include holdersfor engaging the cut sections, such as vacuum holders or clamps. Thetransport member conveys the sections from the cuffing location to atransfer location, at which the sections are joined to antennas to formRFID inlay stock. Preferably the antennas are carried on a webstock.

In the preferred operation of this converting assembly, the transport ofthe RFID webstock, the operation of the cutter member, and theengagement of the sections by the transport member, are controlled so asto increase the pitch of the RFID chips from a relatively narrow pitchto a relatively wide pitch. Preferably the converting assembly increasesthe down-web spacing of the chips. In one embodiment, the transport ofthe RFID webstock may include a shuttle that induces periodic forwardand retrograde motions of the RFID webstock. Preferably, the motion ofthe transport member at the transfer location matches the motion of anantenna-carrying webstock, to register the sections with respectiveantennas.

This converting assembly may act upon an RFID webstock containing asingle lane of chips (which may have been slit from a webstock with aplurality of lanes of chips). In this case, a plurality of suchconverting assemblies would be provided, one for each lane of chips.Alternatively, the converting assembly may act upon webstock containinga plurality of lanes, wherein each severed section would include across-web column of chips.

At the transfer location of the converting assembly, the sections may besubjected to one or more of the following to facilitate joinder toantennas: heat, pressure, and actinic radiation. Conductive ornon-conductive adhesive may be employed to bond chips to antennas. Alamination member such as a roller or belt may form a pressure nip orextended pressure zone to ensure a durable bond between microelectronicelements and antennas. The configuration of chips within respectivesections, and the configuration of antennas and other structures, may bedesigned to minimize mechanical stress on chips during pressure bonding.

In accordance with one illustrative method implementing the presentinvention, a high pitch density RFID webstock (or sheetstock) containingsemiconductive chips is provided and, in a continuous process, a webbearing relatively widely spaced antennas is provided to receiveindividual chips, with the pitch of the chips being changed or greatlyincreased, as the input web is die cut. The resultant individual chipsare associated with corresponding antennas forming an RFID inlay stock.

The RFID webstock includes an array of chips each with associatedcircuits. In one embodiment, the array of chips of the RFID webstockforms a regular pattern such as an orthogonal pattern of down-web rowsand cross-web columns. In this method, the RFID webstock is severed orseparated into a plurality of sections each including one or more of thechips, and these sections are then joined or laminated to an antennalayer to form an RFID inlay stock. This RFID inlay stock may then bejoined to other layers to form an RFID label stock or tag stock whereineach tag or label preferably includes a single chip. An RFID label stockor tagstock may be a multi-layer structure. A facestock printable layermay be an upper layer that forms a top surface of the substrate. Thelabel stock or tag stock may also include a bottom layer such as arelease liner or second facestock.

Features of the invention may include the use of a special substrate forthe RFID microelectronic stock, which is easily die cut, has dimensionalstability, thermal stability and/or other desirable properties asdiscussed heretofore. A preferred substrate is amorphous thermoplasticmaterial that may be in the form of a flexible web capable of beingwound about a core. Alternatively, the substrate for the RFIDmicroelectronic stock may comprise paper or other thin flexiblematerial.

In one embodiment of the invention, the RFID webstock contains an arrayof recesses, nominally each of which contains a respective chip. Therecesses may be at least about 5 μm deep in some embodiments, and arecess may have a substantially rectangular bottom surface and fouroutwardly sloping side walls. Alternatively, the RFID webstock may bewithout recesses, wherein the chips are secured to unindented surfacesof the webstock.

This Summary of the Invention summarily describes certain aspects of theclaimed subject matter, but is not a complete description of theinvention. The Detailed Description, Drawings and the claims furtheridentify and describe features and aspects of the invention.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 illustrates a pattern of embossed wells on the surface of aportion of a web, into which small electronic blocks of complementaryshape may be embedded;

FIG. 2 illustrates a small electronic block embedded in a well in asection cut out from an embossed substrate;

FIG. 3 illustrates an RFID label adhered to a substrate;

FIG. 4 is a cross-sectional view of one embodiment of a multi-layerconstruction formed during the manufacturing process;

FIG. 5 is a cross-sectional view of the multi-layer construction of FIG.4 upon die-cutting, after face material, adhesive and liner have beenadded;

FIGS. 6A, 6B and 6C are views of an RFID section attached to antennas;

FIG. 7 is a perspective view of an antenna web;

FIG. 8 illustrates a process of applying RFID sections to antennas on aweb;

FIG. 9 illustrates steps in a process for forming RFID labels;

FIG. 10 illustrates a process for indexing RFID sections to antennas ina vertical or machine direction;

FIG. 11 is a detail of the process of FIG. 10, illustrating inparticular a die and anvil arrangement;

FIG. 12 is a detail illustrating a die and anvil arrangement.

FIG. 13 illustrates an alternative arrangement utilizing a belt androllers;

FIG. 14 is a simplified diagram illustrating components of a system formanufacturing RFID labels;

FIG. 15 is another diagram illustrating components of a system formanufacturing RFID labels; and

FIG. 16 is a further diagram illustrating components of a system formanufacturing RFID labels.

DETAILED DESCRIPTION OF THE INVENTION I. Introduction

By way of overview, a low cost method of RFID label or tag utilizes atleast three elements. One element is an RFID webstock or RFID sheetstocki.e. a continuous web or sheet that contains microelectronic elements orRFID chips in an array, as well as electrical connectors for the chips.In the method of the invention, the webstock or sheetstock is separatedinto a series of “sections” each of which may be incorporated in a givenRFID label or tag. Typically, each section includes one of the RFIDchips, as well as electrical connectors for that chip. In oneembodiment, the RFID webstock or sheetstock includes a microembossedarray of recesses with the RFID chips secured within these recesses;alternatively the chips may be secured to unindented surfaces of theRFID webstock or sheetstock. Note: The present patent applicationinterchangeably uses the terms of RFID “chips”, “IC's”, “microelectronicelements”, and in certain cases “blocks” in reference to these elements,whether they are embedded in the webstock or sheetstock, or mounted toan unindented surface of the stock.

The method of the invention is adapted to the use of RFID webstock andRFID sheetstock as a carrier for RFID chips, the former being highlypreferred. The term “RFID microelectronic stock” is used herein toencompass both RFID webstock and RFID sheetstock. These terms identifythe webstock or sheetstock including RFID chips and electricalconnectors, but before joining to antennas. Once the individual chipsare associated with corresponding antennas, this patent application usesthe term “RFID inlay” to identify individual chip-antenna assemblies,and the term “RFID inlay stock” to identify a webstock containing suchRFID inlays.

Another element is a continuous web of a plurality of antennas madefrom, for example, copper, silver, aluminum or other thin conductivematerial (such as etched or hot-stamped metal foil, conductive ink,sputtered metal, etc.). A third element is a continuous web or sheet ofselected materials used to support and protect the RFID inlay stock,and/or to provide usable form factors and surface properties (e.g.printability, adhesive anchorage, weatherability, etc.) for specificapplications.

The RFID microelectronic stock contains an array of chips at a pitchdensity that can be considerably higher than the pitch density in anRFID inlay stock that is formed using this RFID microelectronic stock.This high density can provide significant advantages, such asfacilitating the placement of microelectronic elements using an FSAprocess, or other chip placement process. Preferably, the pitch densityof the chips in the RFID inlay stock is the same as the pitch density ofthe chips in final tag or label stock. However, it is possible furtherto adjust the pitch density of the individual inlays and chips as theyare integrated into the final tag or label stock.

A series of antennas are formed on a continuous web made of film, coatedpaper, laminations of film and paper, or other suitable substrate.Preferably, the pitch density of the antennas is engineered to thespecific dimensions of the label or tag within which it will be formed,and independent of the pitch density of the sections.

The microelectronic stock and the antenna web are transported through aconverting process that indexes and individualizes the microelectronicsections to a position associated with each antenna. The process affixesthe sections to the antenna using conductive inks or adhesives appliedto the antenna web, forming the RFID inlay stock. In the preferredembodiment, the inlay stock includes a matrix surrounding the sections,which may be discarded. Alternatively, the inlay stock may be butt cutso as to eliminate a matrix between adjacent sections (e.g. in the downweb direction, or in the cross web direction).

The RFID inlay stock is then laminated above and/or selected label ortag materials made of films, papers, laminations of films and papers, orother flexible sheet materials suitable for a particular end use. Theresulting continuous web of RFID label stock or RFID tag stock may thenbe overprinted with text and/or graphics, die-cut into specific shapesand sizes into rolls of continuous labels, or sheets of single ormultiple labels, or rolls or sheets of tags.

Considering now details of specific embodiments, FIG. 3 illustrates asubstrate 100 onto which an RFID label 102 has been adhered. Thisembodiment of a label includes an upper, printable surface 104, andprinted text and/or graphics 106.

FIG. 4 is a cross-section of a multi-layer label stock or tag stock fromwhich RFID labels and/or tags may be formed. The embodiment includes atop web or facestock layer 400 for carrying printing. A section 402 isprovided in conjunction with a center web 404, onto which an antenna 408(e.g. of conductive ink or foil) is printed, sputtered, laminated orotherwise deposited. A layer of adhesive 406 adheres the facestock 400to the inlay web 404.

FIG. 5 illustrates the multi-layer structure of FIG. 4 as adapted to becut into a label. A layer of adhesive 414 adheres the inlay web 404 toanother layer of facestock material 412. A layer of pressure sensitiveadhesive 414 underlies the facestock layer 412, and is covered with asilicone-coated release liner 416. Areas at which the label is cut areindicated by arrows 419 and 420.

A general purpose, permanent pressure sensitive adhesive or a laminatingadhesive is preferred for adhering the layers of facestock together. Awide variety of permanent pressure sensitive adhesives are well known inthe art. The pressure sensitive adhesive may be one of any number ofdifferent types of adhesives, such as acrylic and elastomeric pressuresensitive adhesives. If the label construction illustrated in FIG. 5 isto be printed in a printer that generates high heat, such as a laserprinter, the adhesive layer 414 may be made to be temperature stable,such as is disclosed in Avery Dennison's U.S. Pat. No. 4,898,323,incorporated herein by this reference.

As a further alternative, rather than coating the bottom layer 412 witha pressure sensitive adhesive layer 414, the bottom layer 412 may becoated with a water activated adhesive, a heat activated adhesive, othertypes of adhesives known in the art, or no adhesive at all (in the caseof a tag). Layer 412 could be a printable material, such as paper or acoated polymer, for use in situations where a user wishes to print thefront and/or the back of the label in a printer by omitting theadditional layers 418 and 416 during the laminating and convertingprocess. In the case of a dual sided tag used, for example, on clothing,a hole may be punched in one end of the tag and a plastic fastener,string or other fastening means is inserted through the hole.

The adhesive that is used in layer 418 may be any of a variety ofdifferent types of adhesives, including a water activated adhesive, aheat or pressure activated adhesive, or any other adhesive known in thelabel art. The adhesive layers 406 and 414 are typically permanentadhesives, although various other adhesives may be used.

Suitable materials for facestock 400 include, but are not limited tometal foils, polymer films, paper, and combinations thereof. Thematerials can be textiles including woven and non-woven fabrics made ofnatural or synthetic fibers. The materials can be single-layered paperor film or they can be multi-layered constructions. The multi-layeredconstructions or multi-layered polymeric films can have two or morelayers, which can be joined by coextrusion, lamination, or otherprocesses. The layers of such multi-layered constructions ormulti-layered polymeric films can have the same composition and/or sizeor can have different compositions or sizes. The facestock 400 can beany of the above sheet or film materials.

The label of FIG. 3 is typically die cut, as with a wedge die or othercutting method known in the label art. In FIG. 4, the label is cut so asto include the section 410. The die cut may extend all the way throughthe cross-section of the label or the cut may extend only down to theliner layer 416. In this instance, the liner may be kept as a unifiedsheet of standard sheet size, with one or more removable labels on topof the sheet, as is typical in the labeling art.

For example, the liner 416 may be cut to have dimensions of 8½ by 11inches or 8½ by 14 inches so as to conform to the size of standard paperinput trays for inkjet, laser and other types of standard home/officeprinters; alternatively, the liner 416 can be cut to other dimensions asrequired in specific applications. Each sheet may include a number ofdie cut RFID labels, which may have standard label sizes such as 1 by 2inches, 1½ by 3 inches, or any of the many other standard label sizesknown in the art, or even may be cut to custom size labels.

It is noted that the adhesive layer 418 and the corresponding releaseliner 416 may be omitted, in the event that a tag rather than a label isdesired. A water-activated adhesive or other type of adhesive may beused instead of the pressure sensitive adhesive 414, depending upon thesurface to which the label is to be applied, and/or the bondingproperties that the user wishes the label to have. For instance, asmall-sized RFID label may take the form of a stamp, such as a postagestamp, that may include a layer of water-activated adhesive.

FIGS. 6A-6C illustrate sections 450, 460 and 470, respectively, attachedto respective antennas 452, 462 and 472. The sections bear respectiveRFID chips 454, 464 and 474. The sections may be attached to theantennas in any of a number of different ways, such as crimping,soldering, or bonding with a conductive or nonconductive adhesive, forexample. Preferably, the attachment of sections to antennas forms anohmic connection between electrical contacts of the chip and leads ofthe antenna. Capacitive connections are also possible.

II. Preparation of the Receptor Film

In one embodiment of the invention, the initial step in manufacturing anRFID tag or label forms receptor wells or holes in a polymeric filmsubstrate, herein sometimes called a “receptor film”. In the preferredembodiment, the polymeric film substrate is a material selected from thepreferred class of polymeric films described in commonly assigned U.S.patent application Ser. No. 09/776,281, filed Feb. 2, 2001, entitled“Method of Making a Flexible Substrate Containing Self-assemblingMicrostructures.” The receptor holes are formed in this substrate filmusing the precision continuous embossing process disclosed in the '281patent application. These polymeric materials, and the preferred processfor forming receptor wells, are described below. Alternatively, thepolymeric film substrate may be selected from the polymeric materialsdescribed in Alien Technology Corporation's patent applications, such asPCT International Publication WO 00/55916. Alternative techniques forforming microstructure receptor wells or holes in the polymer filmsubstrate, as described in Alien's patent publications, include forexample stamping and injection molding.

The polymer film includes wells that are filled with tiny electroniccomponent chips via a Fluidic Self-Assembly (FSA) process, such as thatdeveloped by Alien Technology Corporation of Morgan Hill, Calif. Then, aplanarizing layer is coated on top of the filled wells. The purpose ofthe planarization is to fill any gaps that still may be present; toprovide a smooth, flat surface for later processes, such as the etchingof vias; to assure that the microelectronic block elements (i.e. chips)are maintained in position in their recesses on the substrate duringfurther processing steps; and to provide mechanical integrity for thelaminate. “Vias” are then created with etching techniques. The vias arethen coated with aluminum to form a pair of pads on opposite sides ofthe chip for electronic connection. The polymeric film web at this stageof the process, with embedded chips and associated pads, is referred toin the present application as an “RFID webstock” (or in the case of asheet substrate, “RFID sheetstock”).

In a preferred embodiment of this invention, the RFID webstock orsheetstock is then cut or separated into a series of sections each ofwhich include one or more electronic component chips, with associatedplanarization layer and conductive pads. Each cut or separated portionof the RFID microelectronic stock is referred to herein as a “section.”Alien Technology Corporation recognized a principal advantage of the useof RFID sections in this embodiment: They permit the fabrication usingFSA techniques of RFID webstock or RFID sheetstock with higher densityof chips (and hence a lower manufacturing cost) than the density ofarrays of RFID devices into which the chips are to be incorporated. Thusin the case of a grid of chips arrayed longitudinally and transverselyof the web, the pitch of chips (i.e. center-to-center distance betweenadjacent chips) may be different than the pitch of an array of RFID tagsor labels to be formed: (a) in the longitudinal (also called the “downweb”) direction; (b) in the transverse (or “cross web”) direction, or(c) in both directions. The “pitch density” is determined by calculatingthe reciprocal of the product of these pitches. Thus, an example of adownweb pitch is 5 mm, a cross web pitch could be 10 mm, and in thisexample the pitch density could be 200 chips per m².

If the sections separated from the RFID webstock or RFID sheetstock eachcontain a single electronic component chip, with associatedplanarization layer and conductive pads, these sections are then insuitable form to incorporate in individual RFID tags or labels.Alternatively, the sections may contain a plurality of electroniccomponent chips (with electrical connectors). For example an RFIDwebstock may be slit into a series of longitudinal lanes each containinga single row of microelectronic blocks. At a later point in the process,individual sections can be severed or separated from these lanes to formindividual RFID tags or labels. Handling the RFID sections poses variousmanufacturing problems in separating the RFID sections from the RFIDwebstock and in physically integrating the RFID sections into an RFIDinlay stock (and then, label stock or tag stock) in a roll-to-rolllamination process. Applicants have overcome these problems in thepresent invention, as described below.

The size of each individual RFID section is largely independent of thesize of the associated finished label, subject to the constraint thatthe section cannot be larger than the label. In one embodiment, thesection measures approximately 6 mm by 2 mm. In alternative embodiments,the section measures 10 mm by 2 mm and 4 mm by 2 mm, respectively. Thesize of the section may vary, however, and these dimensions are merelyexamples.

III. Method of Manufacturing RFID Labels

Considering now a method of manufacturing RFID labels, one such methodutilizes large rolls of the various layers. That is, the inputs to theprocess include large rolls of facestock; a substrate roll that isprocessed to form the RFID webstock; and a base material roll on whichantennas are printed or bonded, or alternatively a base material rollwith pre-formed antennas; and possibly rolls of other materials.

FIG. 7 illustrates a web 500 into which antennas 510 are printed orotherwise formed. Once antennas are on the web, individual sectionsbearing RFID chips are affixed to the antennas, as FIG. 8 illustrates,In one approach, sections 520 are held against an anvil 530 by a vacuum.The sections 520 are deposited onto contacts 525 for the antennas.

The sections may be affixed to the antenna contacts by means of anadhesive such as a conductive epoxy adhesive. The adhesive may be curedwith heat and/or pressure at 540.

FIG. 9 is a block diagram illustrating steps in one method ofmanufacturing an RFID label using such rolls. At step 600, a roll ofbase film is unwound for printing. At step 602 an antenna is printedonto the base film at a pitch corresponding to the pitch of the labels.At step 604 the performance is tested before the manufacturing processproceeds further. At step 606 a roll of preprinted antennas is rewound.

The cross-web width of the antenna web may be any of a number ofdifferent widths. In one embodiment, the cross-web width is 16 inches.The pitch of antennas and spacing between antennas would depend on theintended label dimensions and spacing of labels on the final labelstock, typically would be in a range from about 0.5 inch to 32 inches. Atypical spacing between adjacent antennas is about 0.125 inch, but suchspacing can be greater or smaller, if desired.

In the second phase of the label manufacturing process (which may becontinuous or discontinuous with the first phase), a roll of RFIDwebstock is unwound at step 608. The configuration of small electronicblock ICs on the receptor film may vary depending on the particulars ofthe IC placement process (such as FSA), the requirements of the RFIDapplication (and associated specifications of the RFID chip and/orantenna), and other factors. For example, there may be a single row ofsmall electronic block ICs along the web, or there may be multiple rows.For reasons of economy, it is typically desirable to put as many ICs onthe web as possible and for this reason small, densely packed IC's(small electronic blocks) are desirable. That is, in one embodiment, the“pitch density” of the small electronic blocks is maximized. Aspreviously noted, the “pitch density” is the reciprocal of the productof the “down web” or longitudinal pitch and the “cross-web” or lateralpitch.

Individual sections are cut or separated from the web at step 610. Thecutting may be accomplished by die cutting or by other cutting methodsin the art, such as laser cutting, perforating, slitting, punching, orother known means that can scribe to specific shapes and sizes. The cutsections are then indexed in such a way as to match the pitch of theantennas (which typically is the same as the eventual pitch of thelabels). The pitch of the labels depends on the size of the labels,which can vary from application to application. Typically, as discussedpreviously, the sections are provided at a predetermined spacing, andmust be “indexed” to match the spacing that is required for the size ofthe particular type of label into which the section will beincorporated. The indexing may affect the down-web spacing of thesections, the cross-web spacing, or both.

As further background, it should be noted that the pitch density of theICs will generally be greater than the pitch density of the finishedlabel sheets. Small electronic block ICs can be packed more closely toone another on their web than the labels. For example, it may bepossible to have an eight inch wide web of small electronic block ICsand a sixteen inch wide sheet of labels, if the pitch of the sectionsbearing the small electronic block ICs is adjusted after the sectionsare cut from the web to match the cross-web pitch of the labels. Theonly requirement is that there be a one-to-one correspondence betweenthe number of lanes of chips, and the number of lanes of labels.

An indexing device can be used to control the relative speed of the webthat bears the ICs, relative to the speed of the web bearing theantennas, so as to space individual IC's appropriately with respect tothe antenna web. This longitudinal (down-web) indexing device brings thesections into alignment with the antennas, so that a section is properlypositioned relative to the antenna and can be bonded to the antenna.

Referring now to FIG. 10, the RFID Webstock 502 from the unwind 608 istensioned and passed between the cutting die “D” and an anvil “A.” Theweb passes through rollers at an in-feed tension isolator 650 and anin-feed drive 652 on its way to cutting die “D” and anvil “A.” The anvil“A” contains vacuum holding stations on its surface that correspond tothe layout of antennas on an antenna web. The anvil includes a hardsurface, and is typically of the same diameter as the die so that asthey rotate together, they are in the same position relative to oneanother on any plane on their surface. The die cuts each individual RFIDsection out from the matrix of surrounding RFID webstock.

Referring to FIG. 11, vacuum anvil A counter-rotates with “D” and “B”which allows the section to be transported from the surface of “D” to aposition at which the section is joined to an antenna, in this case anip between rollers “A” and “B.” The antenna web passes between anvil“A” and base anvil roll “B” which acts as a lamination member. Roller Bhas a stepped surface to accommodate the thickness of the antenna websuch that the diameters of the rollers can be matched to allow forrotational registration and tangency of the roller's surfaces with thesections and antenna web. Rollers “A” and “B” can form a pressure nip tofacilitate the formation of a durable bond between electrical connectorsof the chip, and the antennas. Additionally, heat and/or actinicradiation such as UV radiation (not shown) may be employed. This bondmay be formed or enhanced using conductive or non-conductive adhesive.Additionally, these rollers may be used to crimp the two metal surfaces,of the section and of the antenna, with or without the use of adhesives.Following formation of this bond, the anvil roller “A” completes itsrotation to accept the next sections.

The layout of FIG. 12 would yield a pitch at affixing of approximatelytwice the pitch of the section. Drawn in FIG. 12 is one half of the dieface detail. Therefore, with each die rotation, four (4) consecutivesections are die cut. Die D is made with cutting faces to match thedimensions of the section. Each die section that die cuts individualsections has a leading edge L-1 and a trailing edge L-2, such that L-1cuts the section web at the leading edge of the section, and L-2completes the cut at the section's trailing edge.

For matching section and antenna pitch with optimal press speeds, it isnecessary to select ratios between the number of cutting sections on dieroller D relative to both the pitch of the sections and the pitch of theantenna, and to the relative diameters of rollers D and A.

After passing through the die station 610, the web passes throughrollers at ouffeed drive 654 and at at-feed tension isolator 656, on itsway to rewind 658.

FIG. 13 illustrates an alternative pressure lamination member B, i.e. ametal or polymeric belt, for bonding antennas to sections on anvilroller A′. The use of a rotating belt B′ provides an extended zone ofelevated pressure and/or temperature to facilitate adhesive curing, andformation of a durable, metal-to-metal bond between the antenna andIC-connector structures. One or more additional set of belt or rollercombinations (not shown) can be provided to further extend the zone ofbond formation between the antenna and IC-connector structures.

Referring again to FIG. 11, the vacuum anvil A is generally designed tohave a portion of its rotation with positive vacuum and a second portionwithout vacuum. In addition, a sub-section of the rotational sectionwithout vacuum, designated by P, may be engineered to operate withpositive pressure flow. Each of the three possible air flow sections canbe engineered to be activated corresponding to the position of thesection relative to rotation of A.

As L-2 completes its cutting of the section, vacuum is created at asurface of anvil roller A through ports corresponding to the sectionsize. The section is therefore held against the surface of roller A asit rotates away from its tangent to die D. The matrix from the sectionweb continues in its plane and is rewound as waste. (Alternatively, thesection web can be butt cut, thereby eliminating the matrix).

When the RFID section, held on anvil roller A by positive vacuumapproaches the tangential section with roller B, the vacuum is released,allowing the section to be engaged and held by the adhesive previouslyapplied to the antenna web. If necessary, a positive air flow can begenerated to push the section from the surface of A in section P; thisairflow also may serve to clean the vacuum station. The section thenmoves with the antenna web.

Concerning down web (or longitudinal) indexing of the sections, the RFIDwebstock transport mechanism can be engineered to direct the web ineither the left-to-right or right-to-left direction, on commands from anelectronic controller. During the period commencing when the leadingcutting die surface L1 first contacts the RFID webstock, and ending whenthe trailing cutting die surface L2 ends contact with the webstock, theweb is transported right-to-left at the same speed as the antenna web.In between these cutting cycles, the web transport control provides acontrolled-acceleration left-to-right motion of the web, in order toplace the next uncut section on the RFID webstock in alignment with thenext set of cutting die surfaces L1, L2 on die D. This cycle is thenrepeated.

The roller D and its cutting sections can be configured so that there isa space between each cutting section that allows the section web totravel in the opposite direction from the motion of the die surfacewithout contacting the die surface. By matching the space betweencutting sections with the elapsed time to cycle the section web from onedirection to another, the position of each section can be cut atdifferent pitches relative to the position of each cutting section. Eachcutting section of D can be made on the same pitch as the antenna sothat as the section web shuttles between cutting and non-cuttingsections of die D, each section is transported on anvil roller A at amatched pitch with the antenna that is moving between rollers A and B.This allows for high speed roll-to-roll processing of standardized (andtherefore lower cost) sections, in a manner that can be adapted to avariety of custom layouts as is typically found in labels and tags.

In one version of the apparatus of FIGS. 9-12, the apparatus operates onan RFID webstock containing a single lane of chips, and a plurality ofsuch apparatus is provided corresponding to the number of lanes of chipson the original RFID webstock. These lanes may be slit from the originalRFID webstock, and optionally may be spread apart prior to processing bythe vertical indexing apparatus. Alternatively, the vertical indexingapparatus may act upon an RFID webstock with multiple lanes of chips.

The lanes of the web that bears the sections must also be made to matchthe lateral (cross-web) pitch of the lanes of the web bearing the labelsand the antennas. One way to ensure this “cross-web alignment” is to useone independent web of sections for every one independent web of labelsand antennae. Another approach is to slit the respective webslongitudinally, and then align the slit lanes of sections to the cutlanes of labels and antennae. This can be done using a series ofspreader rolls, much as is done in a conventional slitter assembly.Slitting methods are known and are disclosed in a number of U.S. Patentsincluding, for example, U.S. Pat. Nos. 3,724,737, 3,989,575, 3,891,157,4,480,742, all incorporated herein by reference, and European PatentPublication EP 0 979 790 A2, incorporated herein by reference. Thespreader rolls divert the strands of small electronic block sections toprovide one lane of sections for every lane of labels.

Another alternative approach is to cut the small electronic block web atmaximum pitch density cross-web, and place the resulting lanes on avacuum belt that spreads the lanes. Using apparatus of the typeillustrated in U.S. Pat. No. 4,480,742, one may utilize a continuousexpanding band or belt to separate the lanes in the cross-web direction.Alternatively, a series of laterally spaced belts may undergo increasingspacing to separate the lanes in the cross-web direction.

Concurrent with steps 608-612, the roll of pre-printed antenna isunwound at step 614. Adhesive for fixing the sections onto thepre-printed antennas is applied to the pre-printed antenna roll at step616. The sections, which are indexed in accordance with the pitch of thelabels, are affixed to the antennas at step 618.

A stabilizing resin may be applied to the bonded sections at step 620.The resin of step 620 serves to protect the small electronic blockcomponents and to fix them into place within the label. Also, theinterface between the section and the antenna can be fragile. A resinousmaterial may therefore be dispensed over the interface area, and thencured to a hard finish that stabilizes the interface from breaking fromflexure, fatigue or the like. Examples of suitable resinous materialsinclude silicon filled thermal curing epoxy or clear filled UV-curableacrylic resin. The epoxy or acrylic resin may be dispensed directly ontothe interface area, or may be indirectly dispensed using a transferdevice.

At step 622, one or more sheets of facestock are laminated to the webbearing the antennas and bonded sections. Referring back to FIG. 4, thisstep would, in the particular embodiment of FIG. 4, serve to adhere thefacestock layer 400 to inlay layer 404. Likewise, additional layers suchas face stock layer 412 can be laminated in positions above and/or belowthe inlay layer 404 such as is shown in FIG. 5.

Once the various layers of the label stock have been laminated together,the label stock may be die-cut into individual labels at step 624. Thelabels may also be cut into strips or into sheets, as desired. Thelabels may be rewound onto a take-up roll at step 626.

In the final phase of the manufacturing the die cut labels are unwoundfrom the reel at step 628. Through a slitting operation at step 630, thedie cut strips of labels are sent to individual lines for finalprocessing. After slitting the web into individual strips, the stripsmay be cut into sheets. The sheets may then be packaged and shipped atstep 632.

FIG. 14 is a simplified diagram of a manufacturing process for makingRFID labels. The base film for printing is unwound at station 600′. Theweb bearing the small electronic blocks is unwound at step 608′. Steps610′-620′, which relate to die cutting and affixing the sections, arethen accomplished.

Step 622 is generally accomplished in block 622′, and the die cuttingand stripping steps are accomplished at block 624′. The facestock isunwound at reel 636′, and the adhesive-coated bottom web and releaseliner assembly is unwound at reel 638′. Alternatively unwind 638′ mayprovide only a web of release liner to be laminated to adhesive coateddirectly onto web 500. The laid on labels are rewound at area 626′. Thelabel matrix, which is the extra material left after the die cuttingstep, is rewound at station 634′.

FIG. 15 is a more detailed representation of a manufacturing process ascompared to FIG. 14. FIG. 15 shows a number of different stations thataccomplish various subprocesses. Considering one subprocess that beginsat the left-hand side of the drawing, an unwind station 700 carries theRFID webstock described previously. The RFID webstock is unwound fromstation 700 and enters an in-feed station 702 and then enters aconverting module 704. At the converting module 704, the RFID webstockis die cut into an array of sections, which are affixed to thepre-printed antenna web. The remainder of the webstock (waste matrix) isfed through out feed station 706 and ultimately is rewound onto a reelat rewind station 708.

Another portion of the manufacturing process illustrated in FIG. 15relates to the printed antenna web 500, which is provided in a reel atstation 710. The pre-printed antenna web 500 is unwound from the reel atstation 710, then proceeds to an in-feed station 712. The preprintedantenna web 500 proceeds to a printing or coating station 714, at whichadhesive is applied to the web. The web 500 continues to station 704where the array of RFID sections are affixed to the pre-printed antennasto form an RFID inlay stock 504. The RFID inlay 504 stock proceeds tostation 716, at which the affixing adhesive is post-cured (e.g. for aB-staged adhesive). Methods for curing adhesives are known in the artand, by way of example and not limitation, include heat curing, UV, andinfrared curing methods.

An additional stabilizing resin may be applied at a station 718. Asdescribed previously, the resin may serve to protect the smallelectronic blocks and to stabilize the blocks on the web. A station 720can serve to inspect the RFID inlay stock, and maintain quality control.The RFID inlay stock then continues to an out-feed station 722, andthrough station 724. At station 724, a laminating adhesive may beapplied to the top and bottom sides of the RFID inlay stock. A facestocklaminate 506, which may be optionally pre-printed or which may besuitable for printing at the user's facility, travels through an in-feedstation 726 and then to station 724 and station 728. At station 724and/or 728, the facestock is laminated to the RFID inlay stock. At thesame time a bottom layer 508, which may be pre-coated with a pressuresensitive adhesive on the bottom, is unwound from a station 730. Thebottom layer 508 enters the stations 724 and 728, where the bottom layeris laminated to the web. The bottom layer that is unwound from the reelat station 730 may also include a release liner that covers the pressuresensitive adhesive on the bottom of the layer. The facestock layer isunwound from reel 731.

The fully laminated construction then passes through an out-feed unit732. It is noted that there are two rewind reels-734 and 736. Rewindreel 734 takes up the laid-on labels. Rewind reel 736 takes up the diecut label matrix that is essentially waste material from the process inwhich the labels are cut. The die cutting operation may be carried outat station 728. It is noted that the cutting operation is not limited todie cutting, but may include other cutting techniques, such as lasercutting, perforating, slitting, punching or other methods known in theart.

FIG. 16 illustrates an alternative arrangement in which stations 750,752 and 754 serve to print graphics and/or text to the upper facestockafter the facestock material is unwound from the reel. Three separateprint stations 750-754 are shown to illustrate that the printing can bedone by more than one printhead, such as in multicolor printing, ifdesired. However, it is also possible to print with only one printhead,as appropriate. As compared to the arrangement in FIG. 15, this processof FIG. 16 provides for printing onto the upper facestock in the samemanufacturing line as the other steps in preparing the label stock. Itmay be desirable to print onto the facestock during label fabricationwhen, for example, variable information such as the identificationinformation that is stored on a particular chip is to be printed on thecorresponding label.

However, it is clear from FIG. 15 that the facestocks may be pre-printedbefore the facestock is wound onto the reel. That is, the pre-printingcan be accomplished offsite at another facility or at another locationbesides the manufacturing line that accomplishes the various specificsteps in making the label. Alternatively, the facestock may be partiallypreprinted offsite, with additional printing done in-line.

The foregoing has assumed that the IC or small electronic blocks areprovided on a rolled web that is unwound during the manufacturingprocess. However, as an alternative, the receptor film with microchipsmay be provided in sheet form rather than rolled web form. The sectionsbearing the individual ICs would then be cut from pre-cut sheets, ratherthan from a roll, and these sections could be integrated into an RFIDtag or label stock using a pick and place operation. To regulate thepick and place operation, the position of a section bearing a smallelectronic block may be registered on a corresponding label by, forexample, using a CCD camera to detect a registration or alignment markon or near the label. In lieu of the web-handling equipment illustratedabove (e.g. for the indexing station, and the attaching station), sheethandling equipment may be employed.

The pick and place operation may be performed by a pick and placedevice, which may include mechanical and/or vacuum grips to grip asection bearing a small electronic block while moving it into thedesired location in alignment with the label. It will be appreciatedthat a wide variety of suitable pick and place devices are well known.Examples of such devices are the devices disclosed in U.S. Pat. Nos.6,145,901, and 5,564,888, both of which are incorporated herein byreference, as well as the prior art devices that are discussed in thosepatents.

Alternatively, rotary placers may be utilized to place the sections uponthe labels. An example of such a device is disclosed in U.S. Pat. No.5,153,983, the disclosure of which is incorporated herein by reference.

The integrated circuits or RFID chips may be friction fitted in recessesin the RFID microelectronic stock, or they may be secured therein by theuse of adhesives and/or solder. Electrical connection between the RFIDchips and circuitry to be connected to the antennas may be done withwire bonding, ribbon bonding, tape-automated bonding, lead frames, flipchip bonding, and/or conductive gluing of leads.

IV. Material Properties—RFID Webstock and RFID Sections

It is preferred that the RFID sections be sufficiently rigid so as tomaintain sufficient dimensional stability and stiffness throughout theprocesses. Additional requirements may be imposed on the substratematerial for the RFID microelectronic stock by process used to form thestock (e.g. to form reception walls); and to form conductive anddielectric materials and assorted electrical interconnect structures.Other desirable properties of the webstock are dictated by the processesfor forming the inlay stock and for converting the inlay stock to labelstock, such as: clean, sharp die cutting characteristics; sufficienttensile modulus to avoid undue elongation under tension (typically morethan 500,000 psi); and adequate strength to avoid web breaks duringoperations such as matrix stripping.

When the planarization process of Alien Technologies, as discussedabove, is used, a suitable polymeric film substrate is one that isdimensionally stable at 150° C. for 1 hour, micro-replicable at 260° C.,exhibits good adhesion with the planarizing layer, exhibits goodchemical resistance, the property of laying flat (<0.5″ lift for a 11″sheet), ready removability from the tool, and die-cuttability.

In an alternative embodiment, when the planarization process of AlienTechnologies is not used, a suitable polymeric film substrate is onethat is micro-replicable at <260° C., the property of laying flat, readyremovability from the tool, and die-cuttability.

When the fluidic self assembly process of Alien Technologies is used toform the deposit IC's in reception walls of the RFID webstock, thesubstrate should typically have significant chemical resistance to theFSA process, which includes exposure to DI water, non-ionic surfactantsand bonding agents at about 30° C. for one hour.

A preferred substrate material is an amorphous flexible thermoplasticmaterial suited to forming an array of precise receptor microrecessesthat are formed in the substrate by a continuous embossing process. Inthis regard, Avery Dennison Corporation has developed substrate materialand a method for embossing the substrate with wells that are temperatureand dimensionally stable. This material and methods of embossing thematerial with wells is described in Avery Dennison's PCT internationalapplication no. PCT/US02/02647, which is incorporated by referenceherein.

The substrate material will typically be inert to various industryrecognized solvents, acids and bases used during planarization, maskingand photoresist events. These exposures may run for periods from oneminute to 30 minutes and at temperatures ranging from 300 to 100° C.

The substrate may be selected among materials, however, such as from thegroup consisting of high Tg polycarbonate, poly(ethylene terephthalate),polyarylate, polysulfone, polyether sulfone, poly phenyl sulfone,polyetherimide, and cyclo-olefinic copolymers. It is generally preferredthat the webstock or sheetstock be constructed of a material ormaterials that show clean, sharp die-cutting characteristics. In thisregard, a preferred substrate material is polysulfone, which exhibitsfavorable die-cutting characteristics and other suitable properties.

In another alternative, microembossing or a laser ablation technique canbe used to create cavities in paper instead of a film. In order to havebetter strength and lower compressibility, liner instead of facestockpaper is generally preferred. Microembossing is usually carried outusing a male-female die. The resolution of paper embossing issignificantly less than that of film. When supercalendered Kraft paper(SCK) is compared with polysulfone, the tensile modulus is comparable.This means that with the same web tension and the same caliper, both SCKand polysulfone will stretch to the same extent; however, elongation atbreak for SCK is much less. For paper, moisture sensitivity is aconcern, as this would adversely affect the dimensional stability of anarticle according to the present invention. One preferred alternative ispolycoated paper, such as paper coated with polyethylene orpolypropylene on one or both sides of the paper. This would reduce anydimensional instability as the result of exposure to moisture.

V. Antenna Web

The antenna portions may be formed on the antenna web using a widevariety of materials and processes. For example, one process involvesprinting on the antenna web a conductive material, such as silverconductive ink, in a pattern defining multiple antennae. The ink may beprinted for example using silk screening techniques, such as in a sheetfed or roll operation. The antenna may be printed in a variety of shapesand patterns, such as a symmetrical pattern, a non-symmetrical pattern,a bow tie shaped pattern, a checkerboard shaped pattern, and/or anunequal shaped pattern, or other shapes and patterns known in the art.

The antennae are typically dried and stored on the web in a roll.However, as an alternative, the antennae may be wet printed during theconverting process, and the sections applied directly to the wet printedink. When the ink dries, the ink bonds the sections to the underlyingweb. The ink may optionally include a dopant to increase adhesion. Alayer of pressure sensitive adhesive may be used in conjunction with thewet ink for additional stability.

Suitable methods of forming the antenna include printing conductive ink,sputtering metal, laminating foil or hot-stamping, or any method knownin the art for forming an antenna on a film.

Considering the sputtered metal approach, it is noted that sputteredmetal antennas may be made to be very thin while still achieving desiredsurface resistance or conductivity. In one preferred embodiment of adevice and method according to the present invention, the antenna isformed by metallic sputter coating. Compared to conventional coating ofa 60% filled silver ink, comparable surface resistance can be achievedby sputtering 1/10 thickness of silver. Additionally, there is no dryingrequired as in the case of a silver filled ink coating.

In one preferred embodiment in which the antenna is formed by metallicsputter coating, the sputtering occurs on a 16 in.times.6 in squaretarget at a sputter distance of 4-5 in with a copper or aluminum targetat a web speed of up to 1 ft/min and a web width of 6-10 in. Variousalternatives exist for masking. In a first alternative, masking isapplied on the substrate followed by removal after sputtering. In asecond alternative, a pattern is masked on the web back coated with PSAwhich laminates to the substrate immediately before sputtering, thenstripping immediately after sputtering. In a third alternative, apermanent mask is used that is very close to the substrate web (1 cm orless) so that the divergence of sputter is minimized.

The precision or definition of the printed elements of lines and spacesis critical to the performance of the antenna. With some antennadesigns, conventional printing may not provide adequate resolution,line/space separation or other quality characteristics necessary todeliver engineered performance.

Likewise, control of thickness and smoothness of the printed areas of anantenna are critical to its performance. Variability due to inkformulation, environmental conditions, substrate specifications, processconditions and other factors can impact both the smoothness and finalthickness of printed antennas. Surface tension effects underlie many ofthese variables and place constraints on the amount of ink that can bedeposited, and how closely graphic elements can be positioned to oneanother.

Preferred substrates for the antenna web include, but are not limitedto, high Tg polycarbonate, poly(ethylene terephthalate), polyarylate,polysulfone, a norbornene copolymer, poly phenylsulfone, polyetherimide,polyethylenenaphthalate (PEN), polyethersulfone (PES), polycarbonate(PC), a phenolic resin, polyester, polyimide, polyetherester,polyetheramide, cellulose acetate, aliphatic polyurethanes,polyacrylonitrile, polytrifluoroethylenes, polyvinylidene fluorides,HDPEs, poly(methyl methacrylates), or a cyclic or acyclic polyolefin.Particularly preferred substrates include polysulfone, polyesterpolyarylate, a norbomene copolymer, high Tg polycarbonate, andpolyetherimide.

It can be desirable to utilize a material that does not unduly stretchduring the manufacturing process. For example, it may be desirable toutilize a webstock having a tensile modulus of more than 500,000 psi.

Considering now exemplary dimensions, presented by way of example andnot limitation, in one label embodiment, the section is approximately7-8 mils thick, the antenna coating is about 5-10 microns (0.2-0.4 mil).The antenna may be coated on a plastic film such as Mylar, having athickness of approximately 2-5 mil. The thickness of this particularlabel embodiment, including a release-coated backing sheet, is betweenapproximately 15-20 mils. The purpose of presenting these examplethickness is not to limit the thickness of any of the layers, or of thelabel overall. Rather, it is to illustrate that RFID labels according tothe present invention may be very thin.

These various embodiments of labels incorporating IC's are just severalexamples of different arrangements that can be imagined for an RFIDlabel or tag. Other arrangements are certainly possible, and are withinthe scope of this patent application.

VI. Additional Aspects

It should be understood that the foregoing Detailed Descriptiondescribes particular embodiments to the present invention for purposesof illustration. However, the present invention is not limited to thespecific examples that this Detailed Description provides. Variouschanges and modifications may be made to the labels or to themanufacturing process within the scope of the invention.

For example, in embodiments discussed above, sections are cut from aweb, then applied to another web on which antennae are located. However,it is possible to, for example, apply a section to a web, then print orotherwise locate an antenna onto the section. This may be done by, forexample, printing an antenna on the section after the section is appliedto a web. Or, alternatively, sputtering metal or otherwise forming anantenna onto the section.

Considering further alternative embodiments, various additional layersmay be included in the RFID labels. For instance, there may beadditional layers of cushioning above or below the IC so as to cushionthe component from bumps or shocks during normal use. Water-resistantlayers such as one or more layers of water-resistant polymer may beincluded in the construction. Still other layers can be includeddepending on the particular properties required and the intendedapplication of the RFID device.

Articles according to the present invention can be, for example, aluggage label or tag, a laundry label or tag, a label or tag forcataloging library articles, a label or tag for identifying an apparelproduct, a label or tag for identifying a postal article, a label or tagfor identifying a medical article, or a label or tag for atransportation ticket. As used herein, and as recited above, the term“label” refers to an article according to the present invention thatincludes at an adhesive surface for attaching the article to anotherarticle according to its intended use. The term “tag” refers to anarticle according to the present invention that lacks an adhesive forattachment.

Layers of the label may be bonded together by means other than adhesive.For example, the integrated circuit may be held in place with a hot meltresin or other substance, which could also serve as a bonding agent. Theresin could then take the place of an adhesive layer. Layers may also bebonded together by, for example, ultrasonic welding.

The adhesive surface of the label may include adhesive covering theentire bottom of the label, or may be coated in a pattern, as is knownin the art. The adhesive may be of the sort that is removable so thatthe label may be removed from the substrate after it is applied thereto,or the adhesive may be a permanent type of adhesive for permanentlybonding the label to the substrate. Alternatively, the adhesive may berepositionable, so that the label may be repositioned on the substrateafter it is initially applied. The adhesive may be water-activated,heat-activated, pressure-activated, and/or activated by other means,depending on the specific application for the particular label.Alternatively, the label may have no adhesive on the undersidewhatsoever, as to when the label (or tag) is to be attached to thesubstrate by other means, which could include sewing, welding, heatbonding, mechanical fastening or any other affixing method known in thetag or label art.

Another alternative is to provide a label or tag having more than oneRFID chip. For example, the receptor film may have multiple recesses persection, with one RFID chip per recess. The RFID chips may be arrangedin a row, column or matrix, and may be electrically interconnected withone another.

As another alternative, a label or tag may include electrical and/orelectronic components other than RFID chips. For instance, an RFID labelor tag may include a sensor, a MEMS, or other type of component. Thecomponents may be electrically interconnected to form a circuit. Thetype of electrical and/or electronic components to be used can beselected by one of ordinary skill in the art and depends on the use ofthe label or tag.

It is again noted that the RFID chip does not necessarily need to bepositioned in a well as described in FIG. 2, for example. The RFID chipcould be atop the substrate, rather than in a well, or could beotherwise incorporated into or onto the substrate. For example, the RFIDIC could be a “flip chip” type, wherein the die is made so that exposedcontacts, or pads on the die have bumps on them. In normal flip chippackaging, the die is flipped over and contacted directly into the leadsthat provide electrical contacts for a circuit including the IC. RFIDtag and label constructions using “flip chip” technology are availablefor example from KSW Microtec GmbH, Dresden Germany.

As another example of IC packaging technologies compatible with thepresent invention, the manufacturing method of the invention may be usedwith “lead frame” webs. In this embodiment, the IC would be mounted to aweb with a conductive metal network which may have relatively large areaportions, commonly called pads or flags, for direct contact withsemiconductor chips or dice, and lead elements for facilitatingelectrical interconnection of the chips or dies via intermediate (e.g.,jumper) connections to the antenna.

Consequently, it should be understood that the Detailed Description doesnot describe all of the various changes that might be made to thespecific examples given in this Detailed Description.

1. A method of forming an RFID article, the method comprising:separating an RFID webstock into a plurality of sections, wherein theRFID webstock includes a plurality of electrical connectors, eachelectrically coupled to one or more of a plurality of RFID chips,wherein each of the sections includes one or more of the electricalconnectors and one or more of the RFID chips; securing at least some ofthe separated sections to a transport member; transferring the sectionson the transport member to a moving antenna web, wherein the antenna webincludes a plurality of spaced antennas disposed thereon, and whereinthe transferring includes moving the transport member such that thetransport member has substantially the same speed as the antenna webwhen the sections are transferred from the transport member to theantenna web; and attaching the sections to the antenna web such that thesections are operatively coupled to respective of the antennas.
 2. Themethod of claim 1, wherein the securing includes securing the sectionsto the transport member as the sections are separated from the RFIDwebstock.
 3. The method of claim 1, wherein the RFID webstock alsoincludes a substrate that supports the electrical connectors and theRFID chips; and wherein each of the sections includes a portion of thesubstrate.
 4. The method of claim 3, wherein the substrate includes aflexible material.
 5. The method of claim 3, wherein the substrateincludes a polymeric material.
 6. The method of claim 3, wherein thesubstrate includes paper.
 7. The method of claim 3, wherein the chips ofthe RFID webstock are adhesively coupled directly to the substrate. 8.The method of claim 7, wherein the chips of the RFID webstock arecoupled to a surface of the substrate.
 9. The method of claim 1, whereinthe separating, the transporting, and the attaching are all parts of anautomatic continuous process to form an RFID inlay stock.
 10. The methodof claim 1, wherein the securing includes using vacuum holders of thetransport member to engage the sections.
 11. The method of claim 1,wherein the separating includes cutting the sections from the RFIDwebstock.
 12. The method of claim 11, wherein the cutting includes usingthe transport member as an anvil during the cutting.
 13. The method ofclaim 1, wherein the separating includes butt cutting the RFID webstockto form the sections.
 14. The method of claim 1, wherein the separatingincludes die cutting the RFID webstock to form the sections.
 15. Themethod of claim 1, wherein the separating includes punching the sectionsfrom the RFID webstock.
 16. The method of claim 1, wherein theseparating includes laser cutting the RFID webstock to form thesections:
 17. The method of claim 1, wherein the separating includesperforating the RFID webstock to form the sections.
 18. The method ofclaim 1, wherein the separating includes slitting the RFID webstock toform the sections.
 19. The method of claim 1, wherein the attachingincludes passing the section and the antenna web through a nip betweenthe transport member and a lamination member.
 20. The method of claim 1,wherein the attaching includes bonding respective of the sections andthe antennas to each other.
 21. The method of claim 20, wherein thebonding includes bonding with an adhesive.
 22. The method of claim 21,wherein the adhesive is a conductive adhesive.
 23. The method of claim21, wherein the adhesive is a non-conductive adhesive.
 24. The method ofclaim 21, wherein the bonding includes pressing together the section andthe antenna web.
 25. The method of claim 21, wherein the bondingincludes heat curing the adhesive.
 26. The method of claim 21, whereinthe bonding includes pressing together the section and the antenna web,followed by heat curing the adhesive.
 27. The method of claim 1, whereinthe attaching includes an ohmic coupling of the electrical connectors tothe antennas.
 28. The method of claim 1, wherein the attaching includesa capacitive coupling of the electrical connectors to the antennas. 29.The method of claim 1, wherein the transport member is a roller, andwherein the moving the transport member includes rotating the roller.30. The method of claim 1, wherein the transport member includes a belt.31. The method of claim 1, wherein the RFID webstock, prior to theseparating, has only a single row of the RFID chips; and wherein thechips of the single row are spaced in a longitudinal direction.
 32. Themethod of claim 1, wherein the RFID webstock, prior to the separating,has multiple rows of the RFID chips; wherein the chips of each of therows are spaced in a longitudinal direction; and wherein the rows areseparated from one another in a transverse direction.
 33. A method offorming an RFID article, the method comprising: separating an RFIDwebstock into a plurality of sections, wherein the RFID webstockincludes a plurality of electrical connectors, each electrically coupledto one or more of a plurality of RFID chips, wherein each of thesections includes one or more of the electrical connectors and one ormore of the RFID chips; transporting at least some of the sections on atransport member to an antenna web that includes a plurality of spacedantennas disposed thereon, wherein the transporting includes: securingthe at least some of the separated sections to the transport member;moving the transport member to move the sections to the antenna web,wherein the moving includes indexing a pitch of the RFID sections from arelatively high density on the RFID webstock, to a relatively lowdensity on an RFID inlay stock; and separating the sections from thetransport member; and attaching the sections to the antenna web suchthat the sections are operatively coupled to respective of the antennas;wherein the separating, the transporting, and the attaching are allparts of an automatic continuous process to form an RFID inlay stock.34. The method of claim 33, wherein the RFID webstock also includes asubstrate that supports the electrical connectors and the RFID chips;and wherein each of the sections includes a portion of the substrate.35. The method of claim 34, wherein the substrate includes a flexiblematerial.
 36. The method of claim 35, wherein the substrate includes apolymeric material.
 37. The method of claim 35, wherein the substrateincludes paper.
 38. The method of claim 34, wherein the chips of theRFID webstock are adhesively coupled directly to the substrate.
 39. Themethod of claim 33, wherein the moving the transport member includessubstantially matching speed of the transport member to speed of theantenna web during the separating of the sections from the transportmember.
 40. The method of claim 39, wherein the transport member is abelt.
 41. The method of claim 39, wherein the transport member is aroller.
 42. The method of claim 41, wherein the securing includessecuring the sections to the roller as the sections are separated fromthe RFID webstock.
 43. The method of claim 41, wherein the securingincludes using vacuum holders of the roller to engage the sections. 44.The method of claim 43, wherein the separating includes cutting thesections from the RFID webstock.
 45. The method of claim 44, wherein theseparating includes using the roller as an anvil during the cutting. 46.The method of claim 33, wherein the separating includes butt cutting theRFID webstock to form the sections.
 47. The method of claim 33, whereinthe separating includes die cutting the RFID webstock to form thesections.
 48. The method of claim 33, wherein the separating includespunching the sections from the RFID webstock.
 49. The method of claim33, wherein the separating includes laser cutting the RFID webstock toform the sections.
 50. The method of claim 33, wherein the separatingincludes perforating the RFID webstock to form the sections.
 51. Themethod of claim 33, wherein the separating includes slitting the RFIDwebstock to form the sections.
 52. The method of claim 33, wherein theattaching includes passing the section and the antenna web through a nipbetween the transport member and a lamination member.
 53. The method ofclaim 33, wherein the attaching includes bonding with an adhesive. 54.The method of claim 53, wherein the adhesive is a conductive adhesive.55. The method of claim 53, wherein the adhesive is a non-conductiveadhesive.
 56. The method of claim 53, wherein the bonding includespressing together the section and the antenna web.
 57. The method ofclaim 53, wherein the bonding includes heat curing the adhesive.
 58. Themethod of claim 53, wherein the bonding includes pressing together thesection and the antenna web, followed by heat curing the adhesive. 59.The method of claim 33, wherein the attaching includes an ohmic couplingof the electrical connectors to the antennas.
 60. The method of claim33, wherein the attaching includes a capacitive coupling of theelectrical connectors to the antennas.
 61. The method of claim 33,wherein the RFID webstock, prior to the separating, has only a singlerow of the RFID chips; and wherein the chips of the single row areseparated in a longitudinal direction.
 62. The method of claim 33,wherein the RFID webstock, prior to the separating, has multiple rows ofthe RFID chips; wherein the chips of each of the rows are separated in alongitudinal direction; and wherein the rows are separated from oneanother in a transverse direction.
 63. A method of forming an RFIDarticle, the method comprising: cutting an RFID webstock into aplurality of sections, wherein the RFID webstock includes a plurality ofelectrical connectors, each electrically coupled to one or more of aplurality of RFID chips, wherein each of the sections includes one ormore of the electrical connectors and one or more of the RFID chips;securing at least some of the cut sections to a roller; transferring thesections on the roller to a moving antenna web, wherein the antenna webincludes a plurality of spaced antennas disposed thereon, and whereinthe transferring includes moving the roller such that the roller hassubstantially the same speed as the antenna web when the sections aretransferred from the roller to the antenna web; and attaching thesections to the antenna web such that the sections are operativelycoupled to respective of the antennas; wherein the cutting, thesecuring, the transferring, and the attaching are all parts of anautomatic continuous process to form an RFID inlay stock.